Not Applicable
Not Applicable
1. Field Of The Invention
This invention relates to a medical device delivery systems, namely catheter mounted stent delivery systems. More particularly, the present invention is directed to socks or sleeves used to retain a stent on a stent delivery catheter. The present invention provides for one or more stent end retaining sleeves having a double wall construction. The double wall construction allows the sleeve(s) to be readily and completely retracted off the stent ends during a stent delivery procedure while retaining an extremely low profile relative to the catheter. In at least one embodiment of the invention the double wall sleeve(s) may be characterized as a tube folded over upon itself to form a continuous loop, wherein a portion of the folded over tube overlies an end of the stent and a portion of the tube is engaged to the catheter shaft. The tube may be retracted off of the stent in a number of ways. The tube may be constructed to roll, slide, or other wise retract away from the stent when the stent expands during delivery. The sleeve may be used singly or in pairs with either self-expanding or balloon expandable stents. In the case of a self expanding stent, one or more sleeves may be utilized in conjunction with one or more retractable sheaths. The sleeve(s) may be provided in a variety of lengths to provide partial to full stent coverage. Other inventive aspects and embodiments of the present end retaining sleeves will be made apparent below.
2. Description Of The Related Art
Stents and stent delivery assemblies are utilized in a number of medical procedures and situations, and as such their structure and function are well known. A stent is a generally cylindrical prosthesis introduced via a catheter into a lumen of a body vessel in a configuration having a generally reduced diameter and then expanded to the diameter of the vessel. In its expanded configuration, the stent supports and reinforces the vessel walls while maintaining the vessel in an open, unobstructed condition.
Both self-expanding and inflation expandable stents are well known and widely available in a variety of designs and configurations. Self-expanding stents must be maintained under positive external pressure in order to maintain their reduced diameter configuration during delivery of the stent to its deployment site. Inflation expandable stents may be crimped to their reduced diameter about the delivery catheter, maneuvered to the deployment site, and expanded to the vessel diameter by fluid inflation of a balloon positioned on the delivery catheter. The present invention is particularly concerned with delivery and deployment of inflation expandable stents, although it is generally applicable to self-expanding stents when used with balloon catheters.
In advancing an inflation expandable stent through a body vessel to the deployment site, there are a number of important considerations. The stent must be able to securely maintain its axial position on the delivery catheter, without translocating proximally or distally, and especially without becoming separated from the catheter. The stent, particularly its distal and proximal ends, must be protected to prevent distortion of the stent and to prevent abrasion and/or reduce trauma of the vessel walls.
Inflation expandable stent delivery and deployment assemblies are known which utilize restraining means that overlie the stent during delivery. U.S. Pat. No. 4,950,227 to Savin et al,relates to an expandable stent delivery system in which a sleeve overlaps the distal or proximal margin (or both) of the stent during delivery. That patent discloses a stent delivery system in which a catheter carries, on its distal end portion, a stent which is held in place around the catheter prior to and during percutaneous delivery by means of one and preferably two sleeves. The sleeves are positioned around the catheter with one end portion attached thereto and overlap an end portion(s) of the stent to hold it in place on the catheter in a contracted condition. Each sleeve is elastomeric in nature so as to stretch and release the stent when it expands for implantation. The stent is expandable by means of the expandable balloon on the catheter. During expansion of the stent at the deployment site, the stent margins are freed of the protective sleeve(s). U.S. Pat. No. 5,403,341 to Solar, relates to a stent delivery and deployment assembly which uses retaining sheaths positioned about opposite ends of the compressed stent. The retaining sheaths of Solar are adapted to tear under pressure as the stent is radially expanded, thus releasing the stent from engagement with the sheaths. U.S. Pat. No. 5,108,416 to Ryan et al., describes a stent introducer system which uses one or two flexible end caps and an annular socket surrounding the balloon to position the stent during introduction to the deployment site.
Copending U.S. patent application Ser. No. 09/407,836 which was filed on Sep. 28, 1999 and entitled Stent Securement Sleeves and Optional Coatings and Methods of Use, and which is incorporated in its entirety herein by reference, also provides for a stent delivery system having sleeves. In 09/407,836 the sleeves may be made up of a combination of polytetrafluoroethylene (hereinafter PTFE) as well as one or more thermoplastic elastomers. Other references exist which disclose a variety of stent retaining sleeves.
The entire content of all patents and applications listed within the present patent application are incorporated herein by reference.
This invention provides for one or more low profile double walled stent retaining sleeves which may be readily and fully retracted from a stent during stent delivery. The rolling retractable sleeves of the present invention improve over the prior art by providing a unique sleeve(s) which is designed to completely retract off of the stent during the stent delivery procedure. The present sleeve(s) are double-walled providing the sleeve(s) with the ability to roll and/or are otherwise retracted off of the stent ends by moving, such as by rolling, away from the stent mounting region or balloon along the catheter shaft. The ability of a sleeve to rollingly retract off of the stent allows the sleeve to retain its general shape and low profile throughout the stent delivery procedure.
In at least one embodiment of the invention the inside surfaces of the walls of the double walled sleeve may be lubricious in nature, have a lubricious coating thereon, or define a space which may contain a lubricant. The double walled structure of the sleeves allows each sleeve to be rollingly retracted completely off of a stent during stent delivery and avoids an accordion or wrinkled sleeve profile subsequent to stent delivery. The sleeves may be comprised of a combination of materials to provide the sleeves with a variety of characteristics such as those described in detail below.